During the process, you'll be asked to add Email members: add the email address in which you need to forward the Slack messages.

Once it’s done, use the Slack share function to share the Slack messages in the channel.All the messages posted there will be automatically send out to the email address you’ve added as a member of the email group.

To post a message in the channel without sending it out, just start your message with the emoji :mute: 🔇